Method and apparatus for stressing concrete



' Sept. 9, 1952` R. M. PARBY METHOD AND APPARATUS FOR sTREssING CONCRETE 3 Sheets-Sheet l Inn luna s JNVENTOR. RIOHARO u. Anny /a Y. n Rv w Mv Sept. 9, 1952 R, M PARRY 2,609,586

METHop AND APPARATUS RoR sTREssTNG CONCRETE Filed Dec. 13, 1949 s sheets-sheet z INVENTOR.

RICHARD M. PARRY was ATTORNEY.

Sept. 9, 1952 R. M. PARRY METHOD AND APPARATUS FOR STRESSING CONCRETE 3 Sheets-Sheet 3 Filed Dec. 13, 1949 INVENTOR. mor-mno M. PARRY YM/M ATTORNEY.

Patented Sept. 9, 1952 METHOD AND APPARATS FOR s'rREssiNG CONCRETE i l Richard M. Parry, Teaneclr,` Nr k.1.,jassgnor to Raymond vConcrete Pile Company, New York,-

Y., a corporation of New Jersey application December 13, i949; seri-@1 m4133554 '7 claims. (c1. ca -154) ,1 Y l i .This inventonpertains to methods,v and apparatus, Vincluding equipment and devicesV -for stressing concrete members.g f1`he invention as illustrated and described is applied tothe stressing of a concreteY structure comprising several axially aligned concrete tubular sections, the structure beingadapted to be used, forexample, as a tubular concrete pile or as a conduit `for other purposesfbutit will be understoodvthat the invention is also applicable to'lrthestressing of other formsv of concrete memberssuch as beams and the like. e

By the use of the invention as here' described, the concrete structure is subject to what is generally referred .to as prestressing' but more specificallyror precisely Withthe preferred form of the invention the structure is post-stressed, that is, after ,the concrete of the structure has set. wires or cable's'running through holestherein are highly tensioned by forces reacting against ends of the structure, the Wires then preferably being bondedinpla'cein the holes so that after the tensioning meansis removed, a substantial amount of the tension will remain inthe Wires and serve to' retain the concrete as bonded there- 'GSL under compressionrr'lhus the` structure will have increased strength when loads are applied theretoY tending to subject the concrete or parts thereof to tension.;

lWith the AformA of concrete structureherein shown', the sections thereof have spaced apart aligned holes in their Walls and the structureY is boundtogether bywre cables, one `cable in each hole'and `each cable comprisingagroup of highstrength highly str essed'wires.

According to the methodof the invention, the Wires of each cable arefirst tensioned by one or more pull jacks at one or both endsf the structure. After the Wires are tensioned, they" are gripped by locking devices preferably comprising cones held by spacer means in spaced relation to theendsfof the structure A passage is provided through-the locking means communicating with thehole in the concrete,V the vWalls in suchA passage being temporarily sealed With-'respect to Walls of the hole. Then, While the wires Yare still held under tension, cement grout is introduced under pressure through said passage andl into the hole in the concrete about the Wires, for-bonding same tothe Walls of the hole. After such :grout has setV and bonded'the Wires inY place, the protruding ends thereof may be cut off at said spacermeans andthe locking devices or cones may be removed. The tension in the Wires is then maintained by the adhesive bond between the individual 'Wires of thecable andthe Walls of the holes in theconcrete structure." 'fi 'i i The invention has "a'number of advantages. For example,A 'since the locking devices maybe readily removed after use, same maybereu'sed,

thereby savingV considerable expense;` and.' sincethe 'Wires may beheld under tension entirelyigby reason of the grout bonding of'same alon'ggtlie Walls of the holes in the concrete. the? protruding wire ends maybe cutv off, therebyeliminating` obstructions at thesurface; of the concrete. and also the concrete structure may: be cutolf4 atany point Without in any Way afectingthe prestress-i inglof the concreteat other pointsyandif ataxiy point the structure jor Wires thereinfaretsubjected to injury vor .embody an imperfection',`*that fact will not interfere with the maintenancefof the desired prestressing of the concrete at 'other points. I ,Y i ,1 r"

`Further and other objects, and advantages willi be apparent' from the vspecification :and claims, and. from the Aaccompanying drawings' which illustratewhat is now considered tobe a preferred embodimentv of the'invention' In the drawings: i 1

Fig. A1 shows.,in cross-section,U a 'sectional tube;

ular concrete structure inl 'process oi"f;beingv stressed, with 'locking cones andgjacks illustrated atY both ends of 'the 'cables' Whichrungthrough aligned holes in thesectionsybut if desired. ojne end of .each Vcable may beanchoredjand a single jackused at the unanchored'end; f i. Fig. v2is an enlarged `cross-section of one of the locking cone assemblies andshov'vingithe: end portions of some of'ai group ofrwires-'forming'ia cable;

Fig. Sis a sectional view on line`3=3 OfFig'TZ; 'Fig; 4 isa View similar to Fi'g.;2,'at alater'stage in the operation, with the temporaryjplaster.ofY Paris seal in place, ready' Yfor the injectionpf cement groutyf f L 1 Vvi if Y Fig. 5 isa View on line l5 5 o f Fig. fi, showing the temporary' plaster of Paris seal; j gg Fig. 6 is a View similar-to that of Figibut; showing the parts'after the cement grout 'has been injected. z-, 1 :Fig. 7 is a sectional vi vv online 1-1 offFig.

(Fig. 8v is a sectional viewof a portion tif-, h nished stressed concrete structure.-

-gf K Considering rst :the lokingdevces Which grip thev ,wires after they are Y tensipned. each- 'dvie '(Fig.' 2.);is made up of an extremelyhardinternal cone IOhaving vsharp wire-engaging corrugations 3 lng-cone I2, both cones being of hardened steel. Internal cone I Il is truncated and has a central hole I4 for the passage of cement grout.

The wires forming each tensioning cable are first threaded through holes 2G in the concrete wall 22, with the ends of each group of wires projecting preferably from bothends Aof Vtherholes as indicated at the right in Fig. l.

The external cone I2 is then placed around the outside of the projecting ends of each group of wires, and the corrugated .internal cone .I0 is inserted inside the projecting wires (Figs. l, 2). All wires I8 in each group are then gripped and tensioned simultaneously and evenly `by pull jacks 24 reacting against the Yend of the concrete structure through the external cones I2 and special spacing stools, each of which comprises :an annular seat 26 in contact with the concrete, and legs 28 abutting against cone I2. V

The inner cones II) are then wedged into locking-engagement with the tensioned .WiregrOups by plungers 29 of the jacks. Thepressures on the .wire.tensioning .cylindersof the 'jacks are then released .and the jacks removed.

:Uponrelease of the tensioning, .all wires .I8 `of the cable. contract slightly longitudinally, drawingthe `inner cones l into the outer cones I2, thereby securely .locking Athe tensioned .Wires .between the `cones.

`After the `tensionedcables are thus locked, lthe spaces between zlegs :28 of the spacing stool and around wireszIS .arefilled with a temporary removable lsea-ling material `such Yfor Aexample `.as plaster `:of Paris v 3Q or the likereadily '.frangible isnaterial (Eigsfl and-),. An extension of passage I Litlig; i2.) through .the plaster :isprovided by .a temporary'rodLi-l! (Figa) extending :through and beyond passage `I4 before 'the :plaster-'was poured, and removed after the plaster is set.

-Ilhen,tlkirough a pipe 34 (Fig. 6) ,screwed :into cone I.Il;.-at $2 .(Fig. 2), cement grout 3.6i (Fig. :6) isforcedunder pressure through -passage I4 V(Fig. 2),-zinto hole 20-until holeZQ is fullpof ,-cement, with Wireszla embedded in, the `grou-t.

When the grout has cured LAsuiiiciently, th plaster -ot-Paris seal 30 vis chipped away and the projecting wires .I8 are cutlFig. 48).so Ythat cones |10, -I2 :and the spacing stool 28.-'-28 mayrbe .removed "for, re-use. "Theprojecting wires may be cut off ishort, or they-maybe vbent-over vand fastened within the depression 40 (Figs. .2, .8)

It is to be understood ythat-the invention .is not limited to the :specific embodiment'herein illustratedland described, but .maybe carried `out lin other -ways Y,without departure from 'its spirit :as defined by the following claims.

In `apparatus for the `stressing of concrete members -by the use of -wires and the likezrex.- tending through cavities in the concrete and initially protruding therefrom. the lcombination comprising `clamping means `including .a clamping member having arconical opening adapted to receive protruding portions of the :wires and a conical :clamping -member f adapted .to Vbe received in said opening and to clamp the wires with respecttothe walls of said opening, -a stool member adapted to be positioned between said clamping means and the surface of the concrete, .such stool member.containingV space permitting the Wires to extend from the cavity in the concrete intolsaid clamping means, and a mass of readily removable -temporaryller means forming a bod-y ofjsolid -material in said `space within said stool andlsurrounding the wire portions therein, but

containing a passage for forming a continuation of the cavity in the concrete, said second named clamping member also having a central opening therethrough communicating with said passagel said temporary ller means serving effectively to seal the surface of the concrete surrounding the cavity therein with respect to portions of the clamping lmeans surrounding the wires while kleaving such passage to permit injection of grout `under pressure through the clamping means and illermeans-into the space surrounding the wires ,ingthe cavity in the concrete, and whereby upon removal of said temporary ller means, the wires will beiexposed lthe stool to permit cutting ,thereofgfgor'-releasef of the clamping means.

"2. In the Yprestressing of concrete members by the use Vof -wiresextending through a cavity in the `concrete and initially protruding therefrom, the combination of method steps which comprises: arranging the protruding wire ends about a central space substantially ,coaxial with-:such cavity; tensioning thewires by applying to .fsuch ends tensioning forcereacting against the...concrete; clamping the wires at points ibetweenthe concrete and the -region of Aapplication otsaid force, to temporarily retain .such tension; :rremoving said tensioning force from .the ,wires while vthey Vremain clamped under tension; and also, between Vsuch points Yand the concretefsurfrounding the wires vwith sealing means :which is readily removable and which sur-roundslsaid space to form same into a channel communicatiing with said cavityin the concrete and with sealed 4 clianriel walls extending from the concrete outwardly beyond said clamping anni-nts; tnenintrodueine under pressure through y:Sain channel inte 4Said ,cavity 'afllline ef Ynement grout for bonding the wiresjinjplace in the cavity; 'andaftersuelierentneesetremeving'such sealine VIneens te .expose .the Wires .between the Veenerete endlsnd clamping peints .and A severing the wires as thus exposed, therebyreleasing thewire tension from said clamping Vpoints, ,the (grout thereafter A,retaining rthe wires ,under `tension'ip the eavityanel the tension ofthe Wires. asbended in the .Cavity-holding .tnecenerete .eenipression.

3. In the prestressing of concretegnembersby the nee of wires extending through a .cavity ,in the concrete tand initiallyprotruding therefrom, the .eembineten ef .method .Steps 4vwhich eem prises.: arranging linegnretrudine wire-ends nennt a central space v substantially coaxial. with ,such cavity; tensioning thewires'by applying .tosucjh ende tensenne fierce :reacting against the .eenerete; .clamping ythe wires vin nos'itienafter tensioning ien neinieeneeed #from -tne -eenerete temporarily to retain .Such vtens-ien `and else. between .eue-h Y,peints and the eenerete. `ennrouneins-tne wires withreadily .removable seeline ineens whereby eadepaee -betweenlne wires provides e vchannel eernnnlnieatine .with ,said cavity in Lthe ennemi-eend 'with Sealed; channel Walls extending frein the .concrete eetwaren' berend ,seid elemnlnafneintei tl1en-:intreslneinf under pressure threuen said fenennelfintosaid cavity a; filling of eernent erentier .bending the wires iii-place` in the :cavity: aneignen-enen geen@ has set, :renievine euch .eenling 'menne-ie exnese the wires between the concrete andfsaid clamping :points and severing tine Wires lenposeci, Lthereby releasing the wire tene/len irene said keiarripiiig peints.. the greet thereafter ae# taining the wiresnniier teneien linelleeerilyand the tension of the Wires as bonded in the cavity holding the concrete under compression.

4. In the stressing of concrete members by the use of Wires and the like extending through cavities in the concrete and initially protruding therefrom, the combination of method steps which comprises: tensioning the wire by applying tensioning force to the protruding wire portions, such force reacting against the concrete to place same under compression; clamping said wire portions at a position spaced from the concrete temporarily to prevent release of such tension; providing a spacer between the concrete and the clamping means to hold the latter against being drawn toward the concrete by the wire tension; inserting a tube through the clamping means and through such spacer into communication with the cavity in the concrete; surrounding such tube within the spacer with .a temporary filler to form a body of solid material about the wire portions and between the clamping means and the concrete; then removing such tube and introducing under pressure through the passage left thereby into such cavity in the concrete, a filling of cement groutfor bonding the lengths of wire to the cavity walls in the concrete; thereafter removing suicient of such ller to expose the wire portions at the region of the spacer; and also, after the grout has set, severing such exposedA wire portions, thereby releasing the wire tension from the clamping means, the tension of the Wire as bonded in the cavity then continuing to hold the concrete under compression.

5. In the stressing of concrete members by the use of wires and the like extending through cavities in the concrete and initially protruding therefrom, the combination of method steps which comprises: tensioning the wire in each cavity by applying tensioning force to the protruding Wire portions, such force reacting against the concrete to place same under compression; clamping said wire portions at a position spaced from the concrete temporarily toprevent release of such tension; providing spacer means between the concrete and the clamping means to hold the latter against being drawn toward the concrete by the wire tension; forming with a temporary filler a body of solid material about the wire portions within such spacer means and accessible at the exterior of the spacer but leaving a passage forming a continuation ofthe cavity in the concrete; then introducing under pressure through said passage intosuch cavity a filling of cement grout for bcndingthe lengths of wire in the cavity to the cavity walls; thereafter removing suicient of such filler means to expose the wire portions at the region of the spacer means; and also, after the grout has set, severing such exposed wire portions, thereby releasing the wire tension from the clamping means, the tension of the wire as bonded in the cavity then continuing to hold the concrete under compression.

6. In the stressing of concrete members by the use of a plurality of wires extending through a cavity in the concrete and initially protruding therefrom, the combination of method steps which comprises: arranging the protruding wire ends about an internal clamping element which has an axial passage therethrough and is spaced from the concrete; providing an external clamping element surrounding such arrangement of wire ends; tensioning the wires in the cavity by applying to their protruding ends tensioning force reacting against the concrete; then causing said clamping means to engage the wires and removing said force; providing temporary sealing means surrounding the Wires at the concrete surface while leaving an opening inside the wire arrangement for bringing said passage into communication with the cavity; then, while retaining the wires under tension by said clamping elements, introducing under pressure through said passage and into the cavity a, lling of` cement grout for bonding the wires in the cavity to the cavity walls; and, after the grout has set, removing said sealing means to expose the Wires and severing the wires to release the tension from the clamping elements.

'7. In apparatus for the stressing of concrete members by the use of wires and the like extending through cavities in the concrete and initially protruding therefrom, the combination comprising: wire clamping means; stool means positioned Y between said clamping means and the surface of forming a body of solid material in said space within saidstool and surrounding the wire .there-` in, but containing a passage forming a, continuation of the cavity in the concrete, said clamping means also having a central opening therethrough communicating with said passage, said temporary llei` means serving eiiectively to seal the surface of the concrete surrounding thecavity therein with respect to the clamping means while leaving such passage t0 permit injection of grout under pressure through the clamp-ing means and filler means into the cavity Vin the concrete, and whereby upon removal of said temporary filler means, the wire Will be exposed in the stool to permit severing thereof for release of the wire tension from the clamping means.

RICHARD M. PARRY.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Great Britain Nov. 26., 1941 

